Yes it should be fairly easy to modify your ESP8266 based OpenSprinkler code to run on OSBee 2.0. Here are the main differences I can think of:
– OSBee uses a universal solenoid design, so the control is slightly different from standard OpenSprinkler. In non-latching mode, it’s almost the same, except that the logic is active low (i.e. a low turns on the valve); in latching mode, the COM and zone pins are controlled in pairs to allow voltage to be applied to each zone valve in positive polarity or negative polarity. The OSBee source code (specifically osbeewifi.h and .cpp) obviously shows how this is done. I suggest just following the OSBee code.
– OSBee 2.0 uses 128×64 OLED (SSD1306) display, and it has only one button. Also, it uses PCF8563 RTC (OpenSprinkler uses DS1307), but if you just copy the i2crtc.h and .cpp that is designed to handle with both types of RTCs.